> mydata <- data.frame(id=c(1,2,3,4,5,67,7,8,9), value=c(2,6,23,77,2,"e",4,5,"f"))
> mydata
  id value
1  1     2
2  2     6
3  3    23
4  4    77
5  5     2
6 67     e
7  7     4
8  8     5
9  9     f